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master
src/core/posix_io.c
342 строки
8 KB
Michael Brown
[uaccess] Remove redundant read_user()
21 апр 2025, 20:55
21 апр 2025, 20:55
04d0b2f
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/* * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of the * License, or any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301, USA. * * You can also choose to distribute this program under the terms of * the Unmodified Binary Distribution Licence (as given in the file * COPYING.UBDL), provided that you have satisfied its requirements. */ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); #include <stdlib.h> #include <string.h> #include <errno.h> #include <ipxe/list.h> #include <ipxe/iobuf.h> #include <ipxe/xfer.h> #include <ipxe/open.h> #include <ipxe/process.h> #include <ipxe/posix_io.h> /** @file * * POSIX-like I/O * * These functions provide traditional blocking I/O semantics. They * are designed to be used by the PXE TFTP API. Because they block, * they may not be used by most other portions of the iPXE codebase. */ /** An open file */ struct posix_file { /** Reference count for this object */ struct refcnt refcnt; /** List of open files */ struct list_head list; /** File descriptor */ int fd; /** Overall status * * Set to -EINPROGRESS while data transfer is in progress. */ int rc; /** Data transfer interface */ struct interface xfer; /** Current seek position */ size_t pos; /** File size */ size_t filesize; /** Received data queue */ struct list_head data; }; /** List of open files */ static LIST_HEAD ( posix_files ); /** * Free open file * * @v refcnt Reference counter */ static void posix_file_free ( struct refcnt *refcnt ) { struct posix_file *file = container_of ( refcnt, struct posix_file, refcnt ); struct io_buffer *iobuf; struct io_buffer *tmp; list_for_each_entry_safe ( iobuf, tmp, &file->data, list ) { list_del ( &iobuf->list ); free_iob ( iobuf ); } free ( file ); } /** * Terminate file data transfer * * @v file POSIX file * @v rc Reason for termination */ static void posix_file_finished ( struct posix_file *file, int rc ) { intf_shutdown ( &file->xfer, rc ); file->rc = rc; } /** * Handle deliver_iob() event * * @v file POSIX file * @v iobuf I/O buffer * @v meta Data transfer metadata * @ret rc Return status code */ static int posix_file_xfer_deliver ( struct posix_file *file, struct io_buffer *iobuf, struct xfer_metadata *meta ) { /* Keep track of file position solely for the filesize */ if ( meta->flags & XFER_FL_ABS_OFFSET ) file->pos = 0; file->pos += meta->offset; if ( file->filesize < file->pos ) file->filesize = file->pos; if ( iob_len ( iobuf ) ) { list_add_tail ( &iobuf->list, &file->data ); } else { free_iob ( iobuf ); } return 0; } /** POSIX file data transfer interface operations */ static struct interface_operation posix_file_xfer_operations[] = { INTF_OP ( xfer_deliver, struct posix_file *, posix_file_xfer_deliver ), INTF_OP ( intf_close, struct posix_file *, posix_file_finished ), }; /** POSIX file data transfer interface descriptor */ static struct interface_descriptor posix_file_xfer_desc = INTF_DESC ( struct posix_file, xfer, posix_file_xfer_operations ); /** * Identify file by file descriptor * * @v fd File descriptor * @ret file Corresponding file, or NULL */ static struct posix_file * posix_fd_to_file ( int fd ) { struct posix_file *file; list_for_each_entry ( file, &posix_files, list ) { if ( file->fd == fd ) return file; } return NULL; } /** * Find an available file descriptor * * @ret fd File descriptor, or negative error number */ static int posix_find_free_fd ( void ) { int fd; for ( fd = POSIX_FD_MIN ; fd <= POSIX_FD_MAX ; fd++ ) { if ( ! posix_fd_to_file ( fd ) ) return fd; } DBG ( "POSIX could not find free file descriptor\n" ); return -ENFILE; } /** * Open file * * @v uri_string URI string * @ret fd File descriptor, or negative error number */ int open ( const char *uri_string ) { struct posix_file *file; int fd; int rc; /* Find a free file descriptor to use */ fd = posix_find_free_fd(); if ( fd < 0 ) return fd; /* Allocate and initialise structure */ file = zalloc ( sizeof ( *file ) ); if ( ! file ) return -ENOMEM; ref_init ( &file->refcnt, posix_file_free ); file->fd = fd; file->rc = -EINPROGRESS; intf_init ( &file->xfer, &posix_file_xfer_desc, &file->refcnt ); INIT_LIST_HEAD ( &file->data ); /* Open URI on data transfer interface */ if ( ( rc = xfer_open_uri_string ( &file->xfer, uri_string ) ) != 0 ) goto err; /* Wait for open to succeed or fail */ while ( list_empty ( &file->data ) ) { step(); if ( file->rc == 0 ) break; if ( file->rc != -EINPROGRESS ) { rc = file->rc; goto err; } } /* Add to list of open files. List takes reference ownership. */ list_add ( &file->list, &posix_files ); DBG ( "POSIX opened %s as file %d\n", uri_string, fd ); return fd; err: posix_file_finished ( file, rc ); ref_put ( &file->refcnt ); return rc; } /** * Check file descriptors for readiness * * @v readfds File descriptors to check * @v wait Wait until data is ready * @ret nready Number of ready file descriptors */ int select ( fd_set *readfds, int wait ) { struct posix_file *file; int fd; do { for ( fd = POSIX_FD_MIN ; fd <= POSIX_FD_MAX ; fd++ ) { if ( ! FD_ISSET ( fd, readfds ) ) continue; file = posix_fd_to_file ( fd ); if ( ! file ) return -EBADF; if ( ( list_empty ( &file->data ) ) && ( file->rc == -EINPROGRESS ) ) continue; /* Data is available or status has changed */ FD_ZERO ( readfds ); FD_SET ( fd, readfds ); return 1; } step(); } while ( wait ); return 0; } /** * Read data from file * * @v buf Data buffer * @v max_len Maximum length to read * @ret len Actual length read, or negative error number * * This call is non-blocking; if no data is available to read then * -EWOULDBLOCK will be returned. */ ssize_t read ( int fd, void *buf, size_t max_len ) { struct posix_file *file; struct io_buffer *iobuf; size_t len; /* Identify file */ file = posix_fd_to_file ( fd ); if ( ! file ) return -EBADF; /* Try to fetch more data if none available */ if ( list_empty ( &file->data ) ) step(); /* Dequeue at most one received I/O buffer into user buffer */ list_for_each_entry ( iobuf, &file->data, list ) { len = iob_len ( iobuf ); if ( len > max_len ) len = max_len; memcpy ( buf, iobuf->data, len ); iob_pull ( iobuf, len ); if ( ! iob_len ( iobuf ) ) { list_del ( &iobuf->list ); free_iob ( iobuf ); } file->pos += len; assert ( len != 0 ); return len; } /* If file has completed, return (after returning all data) */ if ( file->rc != -EINPROGRESS ) { assert ( list_empty ( &file->data ) ); return file->rc; } /* No data ready and file still in progress; return -WOULDBLOCK */ return -EWOULDBLOCK; } /** * Determine file size * * @v fd File descriptor * @ret size File size, or negative error number */ ssize_t fsize ( int fd ) { struct posix_file *file; /* Identify file */ file = posix_fd_to_file ( fd ); if ( ! file ) return -EBADF; return file->filesize; } /** * Close file * * @v fd File descriptor * @ret rc Return status code */ int close ( int fd ) { struct posix_file *file; /* Identify file */ file = posix_fd_to_file ( fd ); if ( ! file ) return -EBADF; /* Terminate data transfer */ posix_file_finished ( file, 0 ); /* Remove from list of open files and drop reference */ list_del ( &file->list ); ref_put ( &file->refcnt ); return 0; }